Objectives: Insomnia disorder impacts nighttime sleep and daytime-functioning. The IDSIQ was developed and validated per FDA guidelines, to assess insomnia disorder impact on daytime-functioning.

Methods: Multiple qualitative assessments conducted with insomnia patients (N_total=95) supported cognitive debriefing of the Daytime Insomnia Impact Scale (Buysse, 2007). Iterative item generation, modification/deletion led to development of an interim 18-item IDSIQ-18 for psychometric evaluation. Following a two-week untreated screening period, insomnia patients-(N=114; US, DE, NCT03056053) received nightly zolpidem and completed the IDSIQ-18 (daily electronic Diary), Patient Global Assessment of disease Severity or Impression of Change (PGA-S, PGI-C), and Insomnia Severity Index, (ISI) at D1, D8 and D14 (end-of-treatment); 41-US patients completed exit interviews. An observational “good sleepers” study (N=103) was also conducted.

Exploratory factor and Rasch analyses confirmed the final items and the factor structure of the IDSIQ. Further psychometric evaluation included inter-item correlations, internal consistency, test-retest reliability, responsiveness using relevant anchors, and interpretation of scores by regression analysis at D1.

Results: The analyses resulted in a three-domain (alert/cognition, mood, and sleepiness) 14-item instrument. IDSIQ corrected item-total correlations at D1 and D8 were >0.40. Total and domain score Cronbach’s alpha coefficients were >0.7 indicating internal consistency. Test-retest reliability was acceptable with total and domain score intra-class correlation coefficients >0.7 for PGA-S and PGI-C scales.

Significant decreases (p<0.001) in mean weekly-average total and domain scores between D1 and D8/D14 in patients reporting PGI-C, PGA-S, or ISI improvements indicate IDSIQ is responsive over time. Anchor- and distribution-based methods identified meaningful change thresholds for the total IDSIQ and domain scores. Regression analysis revealed an IDSIQ score increase of 46 (46.082; p<0.0001) for insomnia patients compared with good sleepers.

Conclusions: Content validity and psychometric properties of the IDSIQ were established, delivering the first insomnia daytime-impacts PRO developed with patient input and validated per FDA guidance.